1. Field of the Invention
The present invention relates to a feeding bobbin for winding a thermal transfer sheet or an image receiving sheet on which an image is to be formed using the thermal transfer sheet, and a method for repeatedly recycling the feeding bobbin.
2. Prior Art
Various thermal transfer methods have hitherto been known in the art. In these thermal transfer methods, a color transfer layer is formed on a substrate to prepare a thermal transfer sheet. The thermal transfer sheet is put on top of an image receiving sheet, and the assembly is heated in a character, figure, pattern or other image form, for example, by means of a thermal head from the backside of the substrate of the thermal transfer sheet to thermally transfer the color transfer layer onto the surface of the image receiving sheet. The thermal transfer methods are roughly classified according to the construction of the color transfer layer into two methods, i.e., thermal dye sublimation transfer (sublimation-type thermal transfer) and thermal ink transfer (heat-fusion transfer). In the thermal dye sublimation transfer method, a color transfer layer comprising a dye, which is thermally sublimable or transferable, supported by a suitable binder is first formed on a substrate to prepare a thermal transfer sheet. The thermal transfer sheet is put on top of an image receiving sheet, and the assembly is heated from the backside of the thermal transfer sheet to thermally transfer the dye contained in the color transfer layer onto the surface of the image receiving sheet. In this case, the image receiving sheet has on its surface a receptive layer which can be easily colored with a dye. On the other hand, in the thermal ink transfer method, a color transfer layer, which can be easily softened and fused and is transferable upon heating, is first formed on a substrate to prepare a thermal transfer sheet. The thermal transfer sheet is put on top of an image receiving sheet, and the assembly is heated from the backside of the thermal transfer sheet to transfer the color transfer layer onto the surface of the image receiving sheet.
Since the above thermal transfer sheet is continuous, the thermal transfer sheet takes a roll form. In this case, the thermal transfer sheet is generally wound onto a feeding bobbin, and the leading end of the thermal transfer sheet is bonded to and wound onto a wind-up bobbin. In a thermal transfer printer, the thermal transfer sheet is carried from the feeding bobbin to the wind-up bobbin to perform transfer recording on an image receiving sheet.
In a feeding bobbin 1 as shown in FIG. 5, flanges 27, 28, which have an edge guide function for a thermal transfer sheet 10, are provided on a winding shaft 4 so that the thermal transfer sheet 10 can be wound onto the winding shaft 4 in its predetermined place without meandering. The feeding bobbin 1 includes a bearing part 3. A bobbin rotary drive part (not shown) is provided in a thermal transfer printer. The bearing part 3 in the feeding bobbin 1 engages with the rotary drive part, and, upon the rotation of the feeding bobbin 1, the thermal transfer sheet is moved and is carried to the wind-up bobbin side.
In the above-described feeding bobbin, when a thermal transfer sheet having a different width is wound, common practice adopted in the prior art is such that a specialty feeding bobbin corresponding to the width of the thermal transfer sheet is provided, the thermal transfer sheet is wound onto the specialty feeding bobbin, and the specialty bobbin with the thermal transfer sheet wound thereonto is mounted in a thermal transfer printer. Therefore, every time when a thermal transfer sheet having a different size (width) is used, a specialty feeding bobbin for the thermal transfer sheet having a different size (width) should be provided. In this case, further, regarding a small roll winding device for winding the thermal transfer sheet having a different size onto the specialty feeding bobbin for the thermal transfer sheet, the mounting position of an edge guide or the like should be changed to cope with the difference in size (width) of the thermal transfer sheet. This disadvantageously requires time and labor and significantly increases a work burden.
Further, specialty feeding bobbins respectively for thermal transfer sheets different from each other or one another in size (width) should be provided. For this reason, at the present time, when the thermal transfer sheet wound onto the specialty feeding bobbin has once been used up, the feeding bobbin is discarded. The discarded feeding bobbins are in many cases plastic products. Disadvantageously, the disposal of bobbins is not environmentally friendly. The separation and recovery of the bobbin products are cost ineffective. Thus, the prior art technique suffers from many problems. These facts apply to feeding bobbins for winding a continuous thermal transfer sheet, as well as to feeding bobbins for winding a continuous image receiving sheet.